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Subject: Re: [PATCH v2] net: enable wireless core features with
 LEGACY_WEXT_ALLCONFIG
To:     Greg KH <greg@kroah.com>
Cc:     linux-kernel@vger.kernel.org, kernel-team@android.com,
        Johannes Berg <johannes@sipsolutions.net>,
        "David S. Miller" <davem@davemloft.net>,
        Marcel Holtmann <marcel@holtmann.org>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        stable@vger.kernel.org
References: <20190906192403.195620-1-salyzyn@android.com>
 <20190906233045.GB9478@kroah.com>
From:   Mark Salyzyn <salyzyn@android.com>
Message-ID: <b7027a5d-5d75-677b-0e9b-cd70e5e30092@android.com>
Date:   Mon, 9 Sep 2019 07:24:29 -0700
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On 9/6/19 4:30 PM, Greg KH wrote:
> On Fri, Sep 06, 2019 at 12:24:00PM -0700, Mark Salyzyn wrote:
>> In embedded environments the requirements are to be able to pick and
>> chose which features one requires built into the kernel.  If an
>> embedded environment wants to supports loading modules that have been
>> kbuilt out of tree, there is a need to enable hidden configurations
>> for legacy wireless core features to provide the API surface for
>> them to load.
>>
>> Introduce CONFIG_LEGACY_WEXT_ALLCONFIG to select all legacy wireless
>> extension core features by activating in turn all the associated
>> hidden configuration options, without having to specifically select
>> any wireless module(s).
>>
>> Signed-off-by: Mark Salyzyn <salyzyn@android.com>
>> Cc: kernel-team@android.com
>> Cc: Johannes Berg <johannes@sipsolutions.net>
>> Cc: "David S. Miller" <davem@davemloft.net>
>> Cc: Marcel Holtmann <marcel@holtmann.org>
>> Cc: linux-wireless@vger.kernel.org
>> Cc: netdev@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Cc: stable@vger.kernel.org # 4.19
>> ---
>> v2: change name and documentation to CONFIG_LEGACY_WEXT_ALLCONFIG
>> ---
>>   net/wireless/Kconfig | 14 ++++++++++++++
>>   1 file changed, 14 insertions(+)
>>
>> diff --git a/net/wireless/Kconfig b/net/wireless/Kconfig
>> index 67f8360dfcee..0d646cf28de5 100644
>> --- a/net/wireless/Kconfig
>> +++ b/net/wireless/Kconfig
>> @@ -17,6 +17,20 @@ config WEXT_SPY
>>   config WEXT_PRIV
>>   	bool
>>   
>> +config LEGACY_WEXT_ALLCONFIG
>> +	bool "allconfig for legacy wireless extensions"
>> +	select WIRELESS_EXT
>> +	select WEXT_CORE
>> +	select WEXT_PROC
>> +	select WEXT_SPY
>> +	select WEXT_PRIV
>> +	help
>> +	  Config option used to enable all the legacy wireless extensions to
>> +	  the core functionality used by add-in modules.
>> +
>> +	  If you are not building a kernel to be used for a variety of
>> +	  out-of-kernel built wireless modules, say N here.
>> +
>>   config CFG80211
>>   	tristate "cfg80211 - wireless configuration API"
>>   	depends on RFKILL || !RFKILL
>> -- 
>> 2.23.0.187.g17f5b7556c-goog
>>
> How is this patch applicable to stable kernels???

A) worth a shot ;-}

B) there is a shortcoming in _all_ kernel versions with respect to 
hidden configurations options like this, hoping to set one precedent in 
how to handle them if acceptable to the community.

C) [AGENDA ALERT] Android _will_ be back-porting this to android-4.19 
kernel anyway, would help maintenance if via stable. <holding hat in hand>

D) Not an ABI or interface break, does not introduce instability, but 
rather keeps downstream kernels of any distributions from having to hack 
in their own alternate means of dealing with this problem leading to 
further fragmentation.

E) Timely discussion item for LPC?

Sincerely -- Mark Salyzyn